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The device will need to be located using the SetupDiXXX() functions to enumerate all instances of the device's interface and get the device path to them. The path can then be passed to CreateFile() . With the handle that CreateFile() returns, ReadFile() can be used.
"Love people and use things, not love things and use people." - Unknown
"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch
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ok can you give me some example
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how can i use constent of pi instead of value 3.14
#include<math.h>
M_PI is generating error
M_PI is undefined
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Review your post. What file are you including?
Steve
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i am including
#include "math.h"
and want to use constent pi instead of value 3.14
i am using M_PI
it causes error undefined M_PI
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You could try something like this:
#include <math.h>
const double g_PI = 4*atan(1);
Steve
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So the PI is hidden somewhere else?
system
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I don't think it's got it anywhere. M_PI from math.h is a non-standard extension I believe, and it's not present in MSVC6 (I just looked).
Steve
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#define _USE_MATH_DEFINES
#include <math.h>
modified on Friday, August 8, 2008 9:33 AM
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I have a client/Server program, when clinet add to above 500, Our some computer that client installed have a "TCP/IP stack full" error,and this computer don't Communicate with the outside.
Why have this problem,please help we. thanks!
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for the code block below, if the actual object pointed to by the pointer passed to the function is of class B, the the cast would throw an exception? thanks
class B { };
class C : public B { };
class D : public C { };
void f(D* pd) {
C* pc = dynamic_cast<c*>(pd);
}
----------------------------------------------------------
"unzip; strip; touch; finger; mount; fsck; more; yes; unmount; sleep" - my daily unix command list
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No exceptions are throw what dynamic_cast ing pointers. Also note that no cast is needed in your code, much less a dynamic one: a D is a C .
Steve
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yes i know it is an implicit cast (upcast) but what i would like to know is the case when the actual object being pointed to by pD is not a D but B? don't have compiler at the moment.
----------------------------------------------------------
"unzip; strip; touch; finger; mount; fsck; more; yes; unmount; sleep" - my daily unix command list
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Since the method takes a pointer to a D an attempt to call the method with a pointer to B will not compile.
Steve
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am not saying inside the function a method is called ( i know this may not have a practical purpose as to have the object but not use it) just for the sake of argument those are the only lines in the function. not sure but IIRC
*if the actual POINTER is not of type being cast to, it returns a void?
*if the actual object is not of type being cast to, it is okay as long as no method of that object is called (if it is called it results in a compile time error?
----------------------------------------------------------
"unzip; strip; touch; finger; mount; fsck; more; yes; unmount; sleep" - my daily unix command list
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swjam wrote: for the code block below, if the actual object pointed to by the pointer passed to the function is of class B, the the cast would throw an exception? thanks
This will work fine and won't throw any exception.
If you're facing some kind of exception, it may be due to this - if you do Base to Derived casting and if RTTI is not enabled, then you'll face an un-handled exception.
Have a look at here too - http://weseetips.com/2008/06/30/dynamic_cast-throws-unhandled-exception-during-reverse-polymorphism/[^]
Regards,
Jijo.
_____________________________________________________
http://weseetips.com[ ^] Visual C++ tips and tricks. Updated daily.
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Hi all,
I am mew to vc++ environment, in my application i want to get the
currently selected system language so that i can pick the corresponding resource dll for internationalisation.
I tried using
GetSystemDefaultLangID() GetSystemDefaultLCID()
but both resulted in English as the answer
though i change the current language in the system to french,dutch I am getting the same answer as English.
Can anybody suggest me the way to extract the current language set in the system instead of this default language.
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Did you try GetUserDefaultLangID() ?
Documentation here.
Hope this helps,
--Perspx
"The Blue Screen of Death, also known as The Blue Screen of Doom, the "Blue Screen of Fun", "Phatul Exception: The WRECKening" and "Windows Vista", is a multi award-winning game first developed in 1995 by Microsoft" - Uncyclopedia
Introduction to Object-Oriented JavaScript
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hey thats great it worked with GetUserDefaultLangID() but wats the difference between both of these functions??????
Anyways thanks for the info....
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I assume GetUserDefaultLangID() is the current language set but GetSystemDefaultLangID() is the default OS language (possibly the original language of the OS?) I'm not too sure, but glad it works
Regards,
--Perspx
"The Blue Screen of Death, also known as The Blue Screen of Doom, the "Blue Screen of Fun", "Phatul Exception: The WRECKening" and "Windows Vista", is a multi award-winning game first developed in 1995 by Microsoft" - Uncyclopedia
Introduction to Object-Oriented JavaScript
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hariakuthota wrote: though i change the current language in the system to french,dutch I am getting the same answer as English.
It's inevitable that you speak English.
"Love people and use things, not love things and use people." - Unknown
"The brick walls are there for a reason...to stop the people who don't want it badly enough." - Randy Pausch
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After installing VS 2008,
in C:\Program Files\Microsoft SDKs\Windows\v6.0A\Include , there is ddraw.h ,
but where is the correspond .lib file?
There is no ddraw.lib in C:\Program Files\Microsoft SDKs\Windows\v6.0A\lib .
system
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You need the DirectX SDK[^].
The installer will add the appropriate paths to your Visual Studio settings,
but you may want to check to make sure they're at the top of the paths list.
You want to use the DirectX SDK headers/libs, not the ones that come with
the Visual Studio SDK.
Mark
Mark Salsbery
Microsoft MVP - Visual C++
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I've tried DirectX SDK, fine.
But why the ones that come with VS2008 can't be used?
system
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